Mining tool



Sept. 20, R-

METZNER I MINING TOOL Filed. June 11. 1926 2 Sheets-Sheet 1 w $3 I m \M A m NH m 1.. w m N l N \i'n\ H0 INVENTOR' various other materials.

Patented Sept. 20, 1927.

.FFQICE.

ROBERT E. METZNEB, or WHEELING, wnsr VIRGINIA.

MINING TOOL.

Application filed June 11, 1926. Seria1.No. 115,287.

This invention relates to mining tools, and, while designed particularly for use in the mining of coal, it is nevertheless susceptible of use in connection with the mining of The primary object of the invention is to provide a mining tool or machine which has improved means for reciprocating the piston by compressed air and for cushioning the piston at the limits ofits working and return strokes.

A further object of the invention is to provide means for effecting gradual and uniform cushioning of the piston at the limits of its strokes and, further, to provide means of this character which is of simple, economical and compact construction and which is positive and reliable in operation.

A still further object of the invention is to provide cushioning means which is wholly incorporated within the cylinder or cylin: ders of the machine and which is devoid of parts that project eXteriorly of the usual cylinders.

lVith these and other objects in View, the invention resides in the features of construction which will hereinafter be fully described, reference being had to the accompanying drawings, in which Figure 1 is a top plan view of the invention;

Figure 2 is a longitudinal section on line 2, Fig. 1;

Figure 3 is an enlarged detail section taken on line 33, Fig. 2;

Figure 4 is a detail section of one of the check valves; and- Figure 5 is a section on line 55, Fig. 2.

Referring to the drawings, 1 designates the frame of the machine, which is herein shown as equipped with a pair of parallel cylinders 2 having therein pistons 3 of hollow cylindrical, or sleeve. form. .Connesting rods 1 are pivoted at their inner ends at 5 to said pistons and at their outer ends to cranks 6 carried by a crank shaft 7. Said crank shaft is mounted inroller bearings 8 and has cover plates 9 at its ends. The connecting rods 1 and the cranks 6 have ballbearings 10, and cover plates 12 attached by means of screws 13 provide access to the ball-bearings. The cover plates have plugclosed oil openings 11, as shown.

A gear wheel 15 mounted'on the crank shaft 7 is in driven relation to a pinion 16 carried by a drive shaft 17, the latter being driven by a motor 18.

A piston rod 19 is slidablein a bearing 20 formed by a contracted taper-ed extension 21 of a head 22 mounted upon the front end of the cylinder. As illustrated in Fig. 5 of the drawings, keys 24 secured by means of screws 25 .to the piston rod 19 are slidable in key-Ways provided therefor in the hearing- 20, whereby to hold the rod 19 against turning. Drills or cutters 26 are, suitably attached to the outer ends of the rods 19 and may be of any appropriate form.

The extension 21 not only provides a hearing for the rod 19, but. having therein air inlet openings 27 it provides for the ad mission and exhaust of .air with respect to the adjacent end of the cylinder.

A piston 28 rigidly secured to the inner end of the rod 19 is 'reciprocalole within the interior of the piston 3, which latter is of hollow cylindrical form, providing aninternal chamber. The hollow cylindrical piston 3 is closed at its forward end by a head 29 provided; with a stuffing box 30 through which the piston'rod 19 is shiftable, and has in its rear end 3 -a check valve 31. A similar check valve 32 is provided in the head 29.

The valves 31 and 32,,loeing identical in form, a description'of one thereof will suf-' fice. Referring to Fig. 4, it will be noted that a chamber 35 is provided in the piston head for the reception of a ball-valve 33,

one end of said chamber being reduced to form a port 36 which opens into the interiorof the piston 3. A coil spring 37 is disposed between the ball valve 33 and the shoulder which is formed about the inner end of said port 36. The other end of the chamber 35 is enlarged and threaded and has screwed therein a plug 38 having a central bore or port 39 the inner end of which terminates in a seat 10 for said ball-valve. The spring 37 acts not only to cushion the ball-valve, but also to prevent the valve from closing the port 36.

Iii-practice, reciprocating movements are communicated to the piston 3 by the motor 18 acting through the intermediate gearing described. Upon advance movement of the hollow piston 3, the valve 31 is actuated to close and air is thus compressed between the rear head of the piston 3 and the piston 23, and this compressed body of air forces said piston 28 to advance with piston 3, thus iniparting the working stroke to piston rod 19. Upon forward movement of piston 3 relative to piston 28, air is permitted to enter the interior of piston 3 in front of piston 28 through valve 32 which is then unseated. The rod 19 is thus given its working stroke and is also cushioned by the body of confined air referred to.

Vfith return movementof the pisto1r3, valve 31 becomes unseatedfor permitting the admission of air. At the sametime, valve 32 is actuated to close and remain closed during the return movement of piston 3, thereby to permit air between the piston and the head 29 ofthe piston 3 tobe compressed. The piston 28 is actuated rearwardly and cushioned by the body of air so compressed.

As depicted in Fig. 1 of the drawings, the cranks 6 are preferably disposed so that, when one cutter is on its working stroke, the other is on its'ret'urn stroke.

From the foregoing it will be seen that the piston 28 and the attached rod 19 carrying the cutter26 are actuated both forwardly and rearwardly by the bodies of air compressed between opposing faces of piston 28 and the rear and forward heads, respectively, of piston 3, andthat, consequently, an effective means ofcushioning the strokes of piston 28 "is provided, as well as means for cushioning the impact of the cutter.

That is claimed isz- 1. In a mining machine, a cylinder, a hollow cylindrical piston having closed ends reciprocable in said cylinder, means for reciprocating said piston, an inner piston reciprocable within said hollow piston, a cuttercarrying piston rod fixed to said inner piston, and check valves in the opposite ends of said hollow piston whereby, upon reciprocation of the hollow piston, alternately to compress air between opposite faces of the inner pistonand the confronting ends of the hollow piston, thereby to effect reciprocation of the inner piston and to pushion its strokes.

2. In a mining machine, a cylinder, ahollow member having closed ends reciprocable within said cylinder, means to reclprocate said member, a piston reciprocable in the F member and having a rod movable through an endthereof, and check valves in the opposite endsof said memher whereby, upon re+ ciprocation of the latter, alternately to compress'air between opposite faces of said piston and the confronting ends of said member thereby to reciprocate said piston and to cushion its strokes.

3. In a mining machine, a cylinder, a hol- ROBERT B. METZNER. 

